PepperPlatformAudioInputImpl: support audio input device selection.

ppapi/examples/audio_input/audio_input.cc

Index: ppapi/examples/audio_input/audio_input.cc
diff --git a/ppapi/examples/audio_input/audio_input.cc b/ppapi/examples/audio_input/audio_input.cc
index 7aff669e4db31e2f6e21a9523d59059db1deb428..7d156b72e6381d00b6fcde660edc262a66c6507c 100644
--- a/ppapi/examples/audio_input/audio_input.cc
+++ b/ppapi/examples/audio_input/audio_input.cc
@@ -114,6 +114,8 @@ class MyInstance : public pp::Instance {
         audio_input_ = pp::AudioInput_Dev();
       } else if (event == "Stop") {
         Stop();
+      } else if (event == "Start") {
+        Start();
       }
     } else if (message_data.is_number()) {
       int index = message_data.AsInt();
@@ -229,6 +231,16 @@ class MyInstance : public pp::Instance {
     }
   }
 
+  void Start() {
+    if (!audio_input_.is_null()) {
+      if (!audio_input_.StartCapture())

[no longer working on chromium, 2012/03/18 00:38:59]

hasn't this function been changed to void?

[yzshen1, 2012/03/19 21:47:54]

We changed PlatformAudioInput::StartCapture() to return void, but not
PPB_AudioInput_Dev.StartCapture().

As I mentioned in a previous comment, ppb_audio_input_shared maintains a simple
state machine, which makes sure PlatformAudioInput is used in a reasonable way.
So PPB_AudioInput_Dev.StartCapture() will return a boolean value, for example,
PP_FALSE when the device has been closed, etc.

+        PostMessage(pp::Var("StartFailed"));
+    } else if (audio_input_0_1_ != 0) {
+      if (!audio_input_interface_0_1_->StartCapture(audio_input_0_1_))
+        PostMessage(pp::Var("StartFailed"));
+    }
+  }
+
   void EnumerateDevicesFinished(int32_t result) {
     static const char* const kDelimiter = "#__#";